Fix AgentServer response model contracts

specification/ai-foundry/data-plane/Foundry/readme.md

@@ -0,0 +1,5 @@
+# Foundry data-plane TypeSpec
+
+> see https://aka.ms/autorest
+
+This folder contains the TypeSpec for Foundry data-plane APIs.

specification/ai-foundry/data-plane/Foundry/src/sdk-csharp-azure-ai-agent-contracts/client.tsp

@@ -230,6 +230,12 @@ namespace Azure.AI.Projects {
     }
   );
 
+  // ItemMessage spreads OpenAI.Message, whose content is an array. The Responses
+  // input contract also accepts string shorthand, and this client uses ItemMessage
+  // in the merged input/output item union.
+  @@withoutOmittedProperties(OpenAI.ItemMessage, "content");
+  @@copyProperties(OpenAI.ItemMessage, { content: string | OpenAI.MessageContent[] });
+
   // To avoid conflicts with Azure.Response
   @@clientName(OpenAI.Response, "ResponseObject");
 
@@ -262,7 +268,4 @@ namespace Azure.AI.Projects {
   @@access(UpdateAgentRequest, Access.public);
   @@usage(UpdateAgentRequest, Usage.input);
 
-  @@access(OpenAI.ItemCustomToolCallOutput, Access.public);
-  @@usage(OpenAI.ItemCustomToolCallOutput, Usage.input | Usage.output);
-  @@clientName(OpenAI.ItemCustomToolCallOutput, "OutputItemCustomToolCallOutput");
 }

specification/ai-foundry/data-plane/Foundry/src/sdk-csharp-azure-ai-agent-contracts/readme.md

@@ -0,0 +1,5 @@
+# Agent service contracts SDK TypeSpec
+
+> see https://aka.ms/autorest
+
+This folder contains SDK-only TypeSpec projections for Azure AI Agent Service response model contracts. The REST API OpenAPI is emitted from the parent Foundry TypeSpec project.

specification/ai-foundry/data-plane/Foundry/suppressions.yaml

@@ -9,6 +9,12 @@
     - "."
     - "**"
 
+- tool: TypeSpecValidation
+  reason: Design underway for folder structure and tool integration for this area
+  paths:
+    - "."
+    - "**"
+
 # Prior suppression currently superseded by the above:
 
 # - tool: TypeSpecValidation